I recently accomplished the same task and managed to make it work. Here is the code I used:
jsFiddle
jQuery
//Checking if there is a cookie set
if($.cookie('colour')!='')
{
$('body').addClass($.cookie('colour'));
}
$('#accessibility-colours a').each(function(index)
{
$(this).click(function(e)
{
e.preventDefault();
switch(index)
{
case 0:
$('body').removeClass($.cookie('colour'));
$('body').addClass('blackText-whiteBackground');
$.cookie('colour', null);
$.cookie('colour', 'blackText-whiteBackground',{ expires: 7, path: '/' });
break;
case 1:
$('body').removeClass($.cookie('colour'));
$('body').addClass('blackText-yellowBackground');
$.cookie('colour', null);
$.cookie('colour', 'blackText-yellowBackground',{ expires: 7, path: '/' });
break;
case 2:
$('body').removeClass($.cookie('colour'));
$('body').addClass('blackText-pinkBackground');
$.cookie('colour', null);
$.cookie('colour', 'blackText-pinkBackground',{ expires: 7, path: '/' });
break;
case 3:
$('body').removeClass($.cookie('colour'));
$('body').addClass('blueText-whiteBackground');
$.cookie('colour', null);
$.cookie('colour', 'blueText-whiteBackground',{ expires: 7, path: '/' });
break;
}
});
CSS
html, body {font:0.9em/1.1em "Arial", sans-serif}
/* Accesibility Icons */
#accessibility-colours {margin:0px; overflow:hidden;}
#accessibility-blackWhite {background:url(../images/design/icon-accessibility-blackWhite.gif) 0 0 no-repeat}
#accessibility-blackYellow {background:url(../images/design/icon-accessibility-blackYellow.gif) 0 0 no-repeat}
#accessibility-blackPink {background:url(../images/design/icon-accessibility-blackPink.gif) 0 0 no-repeat}
#accessibility-blueWhite {background:url(../images/design/icon-accessibility-blueWhite.gif) 0 0 no-repeat}
#accessibility-colours a {float:left; display:block; margin:6px 0 0; padding:4px; border:0; width:16px; height:16px;}
#accessibility-colours a span {margin:0; padding:0; position:absolute; top:-9999px; left:-9999px;}
.blackText-whiteBackground {background:white; color:black}
.blackText-yellowBackground {background:yellow; color:black}
.blackText-pinkBackground {background:pink; color:black}
.blueText-whiteBackground {background:white; color:blue}
HTML
<div id="accessibility-colours">
<a id="accessibility-blackWhite" href="#" title="Black text / White background"><span>Black text / White background</span></a>
<a id="accessibility-blackYellow" href="#" title="Black text / Yellow background"><span>Black text / Yellow background</span></a>
<a id="accessibility-blackPink" href="#" title="Black text / Pink background"><span>Black text / Pink background</span></a>
<a id="accessibility-blueWhite" href="#" title="Blue text / White background"><span>Blue text / White background</span></a>
</div>
<h1>This is the H1 tag</h1>
<p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam facilisis nibh sed tortor blandit interdum semper leo ullamcorper.
Pellentesque gravida hendrerit accumsan. Mauris pretium blandit augue, suscipit ultricies libero aliquam sit amet. Aliquam egestas eleifend augue,
et hendrerit dolor dictum facilisis. Nulla facilisi. Integer auctor elementum purus id lobortis. Aliquam sit amet sem erat. Integer nec orci risus.
Quisque eu purus augue. Sed vehicula venenatis metus eget molestie. Proin vel ultrices augue. Duis in laoreet tellus. Proin eget gravida purus.
Donec ut placerat velit. Etiam ultrices, nibh nec ultricies iaculis, odio orci porta dui, quis semper nunc ante interdum augue.
Curabitur elementum orci interdum nibh adipiscing blandit. Curabitur diam arcu, semper id facilisis id, tempor et nisi.
Vestibulum nisl dolor, aliquam et posuere ut, tincidunt sed mi.</p>